Method of measuring the viscosity of fluids.



A. L. COLLINS.

METHOD 0 MEASURING THE VISCOSITY OF FLUIDS.

APPLICATION FILED AUG-26.1914.

IN I/E /V TOR 1 QQQ, 142a WITNESSES.-

sAn

METHOD OF MEASURING THE VISCOSITY OF FLUIDS.

Specification of Letters Patent.

Patented May 1, 1917.

Application filed August 26, 1914. Serial No. 858,700.

To all whom it may concern:

Be it known that I, ARTHUR LEE 'COLLINS, a citizen of the United States, residing at San Francisco, county of San Francisco, State ofCalifornia, have invented a new and useful Method of Measuring the Viscosity of Fluids, of which the following isa specification.

My invention relates to a method of measuring the resistance to flow offered by fluids in motion. Every known fluid offers a resistance, analogous to friction, to the relative sliding motion of any two adjacent layers. The physical property of the fluid to which this is due is commonly called viscosity.

In the analysis of the cause of fluid resistance there are two terms more frequently used, namely, adhesion, or the force causing a liquid to adhere to a surface, cohesion, or the force causing the integrate particles of the liquid to adhere to each other. Surface tension is probably the resultant of cohesion and is a force which tends to retain and define the surface of a liquid in contact with another liquid or gas.

In the fiowof liquids in tubes, the portion of the liquid in the central zone of the tube is subjected to the resistance offered by cohesion. On the other hand, the layers, adjacent to the walls, are subjected to the influence of both adhesion and cohesion. The re-- sistance offered to the liquid when the liquid is in motion is due to adhesion and cohesion. The layers of the liquid in the proximity of the tube walls are subjected to a greater resistance than the layers in the central zone of the tube.

I have devised a simple and novel method whereby the relative viscosity of a liquid, in contact with difierent kinds of surfaces and under different temperatures, and the relative viscosity of liquids with varying thicknesses of films under different conditions of temperature and in contact with different surfaces can be determined.

In the accompanying drawing, Figure 1 is a vertical section of an apparatus for carrying out my improved method; Fig. 2 is a similar view of a modification thereof.

In Fig. 1 A is a tube, C is a stopper. M is a transparent wall in theyicinity of the surface H of the liquid. E is a vessel containing the fluid to be tested. T is a tube con-- nected to a suction pump. The pump is not shown. The tube T projects into the main tube an inch more or less. First, the fluid the liquid.

In Fig. 2, A is a tube closed at the bottom D and filled to a point H with the fluid to be tested. T is a tube for the purpose of inserting an air column taken from an air pump. The pump is not shown. The rate of travel of the column of air in the tube is a measure of the viscosity of the liquid.

The ap aratus, or any portion of the same, may be 0 glass, metal, or composition of materials.

The apparatus is not limited by shape and size, nor the enlargement, alteration, extension and rearrangement of any part thereof. The forms of apparatus that can be devised are unlimited.

The moving column may consist of air, gas or substance with buoyancy different from the buoyancy or gravity of the fluid to be tested.

By providing tubes of different diameters, and tubes with surfaces of different materials, and testing the liquids at different temperatures, the characteristic viscosity relations of the liquid can be established for the given conditions.

I claim as my invention:

1. The method of testing the viscosity of liquids which consists in admitting to the lower end of a tube filled With the liquid abubble of air or gas and noting the time required for the bubble to rise a determined 5 distance. i

2. The method of testing the viscosity of liquids which consists in elevating a tube filled with the liquid and having its upper end closed against the admission of atmos- 'pheric pressure and its open lower end im- 10 

